Hydrophobically modified ethylenediaminetriacetic acid (EDTA) chelating surfactants, salts thereof, and methods for making these compounds are taught, for example, in U.S. Pat. Nos. 5,177,243, 5,191,081 and 5,191,106 (all assigned to Hampshire Chemical Corp.)
U.S. Pat. No. 5,250,728 to B. A. Parker et al., (assigned to Hampshire Chemical Corp.), teaches a novel route of synthesizing the hydrophobically modified ethylenediaminetriacetic acid.
U.S. Pat. No. 5,284,972 to B. A. Parker et al. (assigned to Hampshire Chemical Corp.) teaches a synthetic route leading to the salts of the hydrophobically modified ethylenediaminetriacetic acid which are the novel chelating surfactants applied by the subject invention.
Inform, Vol. 6, No. 10 (October, 1995, J. Crudden and B. Parker) teaches the physical and physiological properties of the novel chelating surfactants. Mild skin cleansers and mild shampoos are among the potential applications, as discussed in the articles.
Although these novel EDTA-derived surfactants are ultra-mild to skin, inclusion of the surfactants into a personal washing bar is fraught with difficulties. For example, the lather produced by the chelating surfactant alone is not as satisfactory as that of a conventional anionic detergent (e.g., sodium lauryl ether sulfate). Further, aqueous solutions of the EDTA surfactants at the concentrations relevant to the personal washing have a viscosity which is too low to deliver the desired sensory cues.
By this invention, applicants have formulated these chelating surfactants into specific skin cleansing formulations using specific routes of processing such that lather performance and other desired user properties are not sacrificed.